1. Field of the Invention
The present invention relates to a transfer apparatus for transferring an angular substrate or plate, such as a glass substrate or plate for use in a liquid crystal display, for example, and a transfer method thereof.
2. Description of Prior Art
Conventionally, a glass substrate or plate for use in the liquid crystal display is obtained by cutting one large-sized piece of glass plate or substrate, after treating it with processes of applying photo-resist thereon, drying, and further exposing and developing thereof, into glass substrates of sizes as required for a final product.
For applying various types of processes upon such a large-sized glass plate, after completing a process at one process station, it must be transferred to another process station by means of a transfer apparatus.
FIGS. 7(a) and (b) show a plan view and a side view, respectively, of the conventional transfer apparatus, wherein the transfer apparatus is constructed so that hooks 101 . . . are provided on a pair of transfer arms 100 for supporting an angular substrate W at a lower side surface portion thereof.
For transferring the angular substrate W with use of such the transfer apparatus as mentioned above, the transfer arms 100 are arranged to be spaced further apart from each other than the width of the substrate, the height of the apparatus is adjusted so that the hooks 101 . . . of the transfer arms come to be a little bit lower than the angular substrate W which is supported by supporting jigs 102, such as pins, chucks, etc., and next the transfer arms 100 are moved in a horizontal direction so as to move the hooks 101 . . . to a position below the angular substrate W. Thereafter, the transfer arms 100 are lifted up, or alternatively the supporting jigs 102 are lowered, so that the angular substrate W is supported by the hooks 101 . . . and under that condition, the angular substrate W is transferred to the next station by moving the transfer arms 100.
However, the glass substrate or plate for use in the liquid crystal display is thin, having a thickness of, for example, 0.7 mm, has a large planar surface area, and flexes or distorts under it's own weight when suspended in a horizontal plane, hanging downward at the central portion thereof, as shown in FIG. 7(b) In this condition the substrate sometimes interferes with the jigs so that the substrate cannot be transferred, or the flexing brings about a crack in the substrate.
Particularly in recent years the size of the display portion of the typical liquid crystal display has had a tendency to be manufactured to be larger, while at the same time it has become common that a glass plate or substrate having one side exceeding 1.000 mm in length before the cutting thereof is utilized. For example, lifting the glass substrate having the sizes 960 mm.times.1.100 mm.times.0.7 mm by means of the conventional transfer apparatus, the substrate is bent or distorted by about 100 mm from the substrate plane at the central portion thereof.